Fire in the Sky: iPhone Ignites on Australian Flight.

An Apple (Nasdaq: AAPL) iPhone 4 began emitting smoke and appeared to spontaneously combust on a recent Regional Express flight to Sydney, Australia.

The phone was emitting a significant amount of dense smoke, accompanied by a red glow, according to Regional Express.

Standard safety procedures were followed and no one on board was injured. The phone was handed over to the Australian Transport Safety Bureau for further investigation.

No such incident had happened on a Regional Express flight before, a spokesperson for the airline said, and there was nothing otherwise significant or unusual about that flight in particular.

Apple did not respond to our request to comment for this story.

Apple Explosions

It's not the first time an Apple product has apparently spontaneously combusted. Reports of flaming iPods and iPhones burning users or starting small fires have come up in the past, such as a 2009 report from Liverpool, England, where a father claimed his daughter's iPod touch exploded; he was reportedly offered a new one on the condition he sign a confidentiality agreement.

That and other reports, such as an iPhone 3G burning a significant hole through a car sear, have not been confirmed by the company.

In some cases it's been found that other technologies are at fault. For example, in 2010, a user reportedly complained that an iPhone 4 caught fire and burned his hand; it was later concluded that a faulty USB port was to blame.

However, when a mobile gadget does flame up on its own, it's often related in some way to the device's battery.

Apple has in the past recalled its first-generation iPod nanos sold between September 2005 and December 2006 because of the risk of batteries overheating. However, the problem isn't limited to Apple or handheld devices.

"There have been several issues with these batteries in the past, although the vast majority of the problems were with laptop batteries," Bill Morelli, director of mobile technologies and convergence at IMS Research, told MacNewsWorld. "A few years back there were several issues with laptop batteries manufactured by Sony (NYSE: SNE) that were related to problems in the manufacturing and ultimately led to a recall,"

Lithium Lags

Part of the reason mobile device battery safety risks persist is because of the highly complex chemistry needed to develop longer-lasting battery power. While advances in areas such as hardware and integrated systems have made giant leaps over the past decade, lithium ion battery technology is still a relatively recent development.

"Battery science is unfortunately a limited science and does not follow advancements likeMoore's Law with semiconductors," Ben Bajarin, director of Creative Strategies, told MacNewsWorld.

In larger-scale products such as battery-powered automobiles, the limitations pose a much greater challenge. On the consumer device level, though, the safety hazards aren't usually so great that a recall is necessary. In the case of an iPhone or another mobile handset, especially, reports of mobile device flare-ups are relatively few and far between.

"There have been no widespread reports of problems with the iPhone batteries, so I suspect this particular incident is more of an anomaly," said Morelli.